Nether

The Nether, also known as Hell or the Slip, is a dimension filled with lava. It allows the player to travel long distances rather quickly, as every block in the Nether maps to 8 blocks in the overworld.

Biomes

The Nether can only generate a single "biome" in this version, that being the Hell biome, later renamed to the Nether Wastes in modern versions.

Generation

The nether generator is very closely related to the overworld generator, sometimes even erroneously so (See the quirks page for more info).

Here's a brief list of all the most important things.

Terrain Noise

• All the same noises with the same octave values exist, with the exception of Tree Density Noise, which is removed.
• The vertical noise scale was changed from 684.412 to 2053.236
• Continentalness and Depth noise are sampled as 3D Perlin noise with a height of 1, ignoring the 2D fastpath introduced in Alpha 1.2.0

  Generator	Octaves	Scale
  Low Noise	16	(684.412, 2053.236, 684.412)
  High Noise	16	(684.412, 2053.236, 684.412)
  Selector Noise	8	(684.412 / 80.0, 2053.236 / 160.0, 684.412 / 80.0)
  Continentalness	10	(1.0, 0.0, 1.0)
  Depth Noise	16	(100.0, 0.0, 100.0)

• The sand, gravel and stone noise maps are unchanged
• Biomes, Temperature or Humidity are not present

Interpolation

• Netherrack is placed instead of Stone
• Ice is not placed at the top-layer of water
• Lava (Still) is placed instead of Water (Still)
• The lava level is 32, with the exception of it being 64 when replacing surface blocks

Biome Blocks

• The top and filler block are always Netherrack by default
• The same algorithm that places Bedrock at the bottom of the world places it at world height (y >= (CHUNK_HEIGHT-1) - rand.nextInt(5))
• If the gravel noise is active, it places Gravel at the top instead of air, and fills with Netherrack
• If the sand noise is active, it places Soul Sand as both the top and filler
• Sandstone is not placed

Caves

The nether caver is identical to the one used for the overworld, with the only exception being that is checks for different blocks.

Overworld	Nether
Stone	Netherrack
Water (Flowing)	Lava (Flowing)
Water (Still)	Lava (Still)

The checks for Dirt and Grass still exist, though neither are replenished, and Lava isn't placed at the bottom of the world.

Population

Please see the nether section on the population page.